Christoph Lofi

General

Dr. Christoph Lofi



National Institute of Informatics
Dr. Christoph Lofi, Room 1401
2-1-2 Hitotsubashi, Chiyoda-ku
Tokyo 101-8430, Japan

Phone:
Email: lofi@nii.ac.jp
Room: 1401

Detail

PLEASE REFER TO MY NEW HOMEPAGE HERE. 

 

This page is not maintained since October 2012, as I moved to NII Tokyo.

Teaching

Lecturer

Assistant

 

Reseach Interests & Projects

Personalization in Databases

My main research interest is personalization of database and information systems. Most of my recent work has been performed within the Apis Project. I have been focusing mainly on Skyline queries which provide an easy-to-use and personalized access to the best objects in a database. However, skyline query result sets may grow dramatically in size with an increasing number of attributes, thus often rendering query result sets useless to users. Furthermore, they lack the desireable ability to compensate between attribute domains. My trade-off skyline aproach provides a solution to those two problems by introducing novell modelling techniques and algorithms allowing the user to specify trade-offs. Trade-offs skylines provide an additional layer of personalization on top of skylines and further reduce the size of result sets.

My addiotional reserach interests and future works focus on personalization of open linked data queries as well as on personalized natural language queries.

Anaqonda Project - Analogy Queries by Ontology-based Data Analytics

 

see www.ifis.cs.tu-bs.de/content/anaqonda

Apis Project

(www.l3s.de/apis/)

The APIS project (Advanced Personalization in Information Services) investigates the impact of personalization technology on future information provisioning. Being interdisciplinary between computer science and cognitive sciences a basic belief of the APIS group is that modern information provisioning needs advanced query processing and optimization techniques using and understanding human preferences, usage patterns, conceptual views and (domain) ontologies. At the same time the architectures for information provisioning have to move from monolithical database systems to more open service-oriented infrastructures.

Academic Programm Committee Memberships

University Committee Memberships

 

Short CV

2011-2012: PostDoc at Technische Universität Braunschweig
2011: Defense of Doctoral Thesis at Technische Universität Braunschweig
2008-now: Researcher at Institute for Information Systems, Technische Universit Braunschweig
2006-2008: Researcher at L3S Research Center, Leibniz University Hannover
2005: Diploma Thesis at Collaborative Software Development Laboratory, University of Hawai’i, Honolulu - Manoa
2002-2004: Assistant Researcher at Fraunhofer Institute for Experimental Software Engineering, Kaiserslautern
2000-2004: Student at University Kaiserslautern

Previous Projects

Prolix

(http://www.prolix-project.eu, 2006-2008)

Hackystat

(http://code.google.com/p/hackystat, 2005)

Publications
2013
Lofi, C., K. E. Maarry, and W. - T. Balke, "Skyline Queries in Crowd-Enabled Databases", Int. Conf. on Extending Database Technology (EDBT), Genoa, Italy, 03/2013. Abstract  Download: 13_edbt_final2.pdf (1.31 MB)
Lofi, C., "Just ask a human? – Controlling Quality in Relational Similarity and Analogy Processing using the Crowd", Crowd-enabled Data and Information Management (CDIM) Workshop at Database Systems for Business Technology and Web (BTW), Magdeburg, Germany, 2013. Abstract  Download: 13CDIM_Final.pdf (611.43 KB)
2012
Lofi, C., U. Güntzer, and W. - T. Balke, "Equivalence Heuristics for Malleability-Aware Skylines", Journal of Computing Science and Engineering (JCSE), vol. 6, no. 3, 09/2012. Abstract  Download: JCSE-2012-0037.pdf (1.97 MB)
Selke, J., C. Lofi, and W. - T. Balke, "Pushing the Boundaries of Crowd-Enabled Databases with Query-Driven Schema Expansion", 38th Int. Conf. on Very Large Data Bases (VLDB), Istanbul, Turkey, in PVLDB 5(6) , 08/12, 2012. Abstract  Download: 267_camera-ready-v3.pdf (1.25 MB)
Lofi, C., and R. Krestel, "iParticipate: Automatic Tweet Generation from Local Government Data", 17th International Conference on Database Systems for Advanced Applications (DASFAA) - Demo Track, Busan, South Korea, 04/2012. Abstract  Download: dasfaa12_iparticipate (211.5 KB)
Lofi, C., U. Güntzer, and W. - T. Balke, "Malleability-Aware Skyline Computation on Linked Open Data", 17th International Conference on Database Systems for Advanced Applications (DASFAA), Busan, South Korea, 04/2012. Abstract  Download: Dasfaa12_Lofi (799.68 KB)
Lofi, C., and W. - T. Balke, "On Skyline Queries and how to Choose from Pareto Sets", Advanced Query Processing, vol. 36: Springer, pp. 15–36., 2012. Abstract  Download: printversion.pdf (415.01 KB)
2011
Lofi, C., U. Güntzer, and W. - T. Balke, "Eliciting Skyline Trade-Offs using Example-Based Heuristics for E-Commerce Applications", IEEE Conference on Commerce and Enterprise Computing (CEC), Luxembourg, Luxembourg, 09/2011. Abstract  Download: Full Text CEC 2011 (689.39 KB)
Lofi, C., "Choosing the Right Thing: Cooperative Trade-Off Enhanced Skyline Queries", PhD Workshop at the International Conference On Data Engineering (ICDE), Hannover, Germany, 04/2011. Abstract  Download: 11ICDE_02.pdf (366.51 KB)
Lofi, C., Cooperative Trade-Off Enhanced Skyline Queries, : Carl-Friedrich-Gauß-Faculty, TU Braunschweig, 2011. Abstract  Download: Dr_Lofi.pdf (735.21 KB)
Homoceanu, S., M. Loster, C. Lofi, and W. - T. Balke, "Will I like it? – Providing Product Overviews based on Opinion Excerpts", IEEE Conference on Commerce and Enterprise Computing (CEC), Luxembourg, Luxembourg, 2011. Abstract  Download: Full Text CEC 2011 (587.95 KB)
2010
Lofi, C., C. Nieke, and W. - T. Balke, "Mobile Product Browsing using Bayesian Retrieval", 12th IEEE Conference on Commerce and Enterprise Computing (CEC), Shanghai, China, 11/2010. Abstract  Download: Fulltext (726.29 KB)
Lofi, C., and W. - T. Balke, "Preference Trade-Offs – Towards manageable Skylines", 22. GI-Workshop Grundlagen von Datenbanken (GvD), Bad Helmstedt, Germany, 05/2010. Abstract  Download: fulltext.pdf (642.42 KB)
Selke, J., C. Lofi, and W. - T. Balke, "Highly Scalable Multiprocessing Algorithms for Preference-Based Database Retrieval", 15th International Conference on Database Systems for Advanced Applications (DASFAA), Tsukuba, Japan, 04/2010. Abstract  Download: Fulltext.pdf (1.01 MB)
Lofi, C., U. Güntzer, and W. - T. Balke, "Efficient Computation of Trade-Off Skylines", 13th International Conference on Extending Database Technology (EDBT), Lausanne, Switzerland, 03/2010. Abstract  Download: Fulltext.pdf (1.08 MB)
2009
Lofi, C., W. - T. Balke, and U. Güntzer, "Efficient Skyline Refinement using Trade-Offs Respecting Don't Care Attributes", International Journal of Computer Science & Applications (IJCSA), vol. 6, no. 5, 10/2009. Abstract  Download: Fulltext PDF (831.91 KB)
Lofi, C., W. - T. Balke, and U. Güntzer, "Efficient Skyline Refinement using Trade-Offs", 3rd IEEE International Conference on Research Challenges in Information Science (RCIS), Fès, Morocco, 04/2009. Abstract  Download: rcis09_final.pdf (540.78 KB)
2008
Lofi, C., U. Güntzer, and W. - T. Balke, "Consistency Check Algorithms for Multi-Dimensional Preference Trade-Offs", International Journal of Computer Science & Applications (IJCSA), vol. 5, no. 3b, pp. 165 - 185, 2008. Abstract  Download: Fulltext-PDF (888.54 KB)
Lofi, C., W. - T. Balke, and U. Güntzer, "Efficiently Performing Consistency Checks for Multi-Dimensional Preference Trade-Offs", 2nd IEEE International Conference on Research Challenges in Information Science (RCIS), Marrakech, Morocco, 2008. Abstract  Download: Fulltext-PDF (555.38 KB)
2007
Balke, W. - T., C. Lofi, and U. Güntzer, "Incremental Trade-Off Management for Preference Based Queries", International Journal of Computer Science & Applications (IJCSA), vol. 4, no. 2, 06/2007. Abstract  Download: Fulltext-PDF (572.96 KB)
Balke, W. - T., C. Lofi, and U. Güntzer, "User Interaction Support for Incremental Refinement of Preference-Based Queries", 1st IEEE International Conference on Research Challenges in Information Science (RCIS), Ouarzazate, Morocco, 04/2007. Abstract  Download: Fulltext-PDF (643.83 KB)
Lofi, C., D. Olmedilla, O. Papapetrou, W. Siberski, J. L. D. Coi, A. Kösling, and E. Herder, "A Model for Competence Gap Analysis", 3rd International Conference on Web Information Systems and Technologies (WEBIST), Barcelona, Spain, 03/2007. Abstract  Download: Fulltext-PDF (103.53 KB)
Balke, W. - T., C. Lofi, and U. Güntzer, "Eliciting Matters - Controlling Skyline Sizes by Incremental Integration of User Preferences", 12th International Conference on Database Systems for Advanced Applications (DASFAA), Bangkok, Thailand, 2007. Abstract  Download: dasfaa07-camRed.pdf (393.17 KB)
2005
Lofi, C., "cGQM - Ein zielorientierter Ansatz für kontinuierliche, automatisierte Messzyklen", Proceedings of the 4th National Conference on Software Measurement and Metrics (DASMA MetriKon 2005), Kaiserslautern, Germany, GI, 11/2005. Abstract  Download: 
Lofi, C., "Continuous GQM: An automated measurement framework for the GQM paradigm", Fachbereich Informatik, Kaiserslautern, Germany, University Kaiserslautern, 08/2005. Abstract